1. Field of the Invention
The present invention relates to an endoscope having a sealed housing and magnetic structures, wherein an inner magnetic structure is coupled with a drive element and an outer magnetic structure is coupled with an adjustment element.
2. Description of Related Art
Endoscopes fitted with a sealed housing may receive, in a protected manner, their susceptible components such as optical lens elements, precision mechanical parts, electronic devices and the like. Accordingly, they are well applicable to medical purposes and shield the internal components from body fluids, sterilizing media, and sterilizing steam.
Displacement devices configured inside the sealed housing illustratively are used to switch valves for lines passing through the housing, drive electrical switches and, in particular, to adjust optical devices such as deflecting mirrors, lens elements, polarizing filters and the like. External control of such devices through the housing wall, however, does raise problems because such a control implemented through sealed, mechanical feedthroughs can be vapor-tight in the long run only at the cost of great difficulties.
As a result, endoscopes of this sort make use of an adjustment device whereby one or several magnetic structures physically engage, through the non-magnetic wall, other oppositely configured internal magnetic structures so as to implement an internal displacement to appropriately drive the corresponding components into adjustment. This design attains a hermetically sealed housing free of any feedthroughs.
Endoscopes of this kind are known from the German patent documents 197 18 189 A1, 195 21 654 A1 and 197 13 276 A1 and also from U.S. Pat. No. 5,836,867.
All these designs apply to continuous adjustment over a given range and require very accurate displacement, which most of the time is implemented by several pairs of mutually interacting permanent magnets. Unfortunately, such designs are very cumbersome. Even so, the are affected by a residual positioning inaccuracy because the outer magnets are unable to position the inner one(s) with 100% accuracy.
It is an objective of the present invention to create an endoscope of the above-mentioned kind of which the design is simple and which offers accurate adjustment.
In the present invention, as in the designs of the state of the art, the outer magnetic structure drives the inner one by its field, that is inaccurately. However, the outer magnetic structure moves the inner magnetic structure against a stop and then moves one step further and secures the inner magnetic structure in an adjustment position and keeps holding it against the stop by means of its fields and thereby keeps it in a 100% accurate position. In the invention, high magnetic forces are attained in much simpler manner.
When using the conventional tubular endoscope housing-wall, the design of the invention may be applied, for instance, to axially adjust a lens element or the like. Moreover, only one position of the drive element might require high accuracy while less accurate displacement corresponding to the state of the art will be acceptable in the remaining range of displacement. This design is very well suited for rotating an internal drive element between two reference positions. Illustratively, this design allows setting a polarizing filter precisely at 0xc2x0 and at 90xc2x0.
In further accordance with the present invention, rotational adjustment is feasible as in the state of the art. However, the drive element is axially held within the housing against a stop. In case a polarizing filter is used, as already mentioned above, it shall therefore be kept axially against a suitable rotation stop. In this manner any mechanical play can be eliminated and a second support need not be used.